Estimating Compressive Strength of Unidirectional CFRP Using Apparent Shear Modulus

Compressive strength of unidirectional CFRP was estimated based on a model of column buckling on elastic foundation. It was shown that the compressive strength based on the column buckling model coincided with the compressive strength based on the fiber kinking model for high fiber volume fraction of the unidirectional CFRP. Apparent shear modulus of a carbon fiber in the in-phase buckling was calculated by the shear and bending deformation of the composite. The apparent shear modulus was decreased depending on the ratio of kink band length to the fiber diameter. Compressive strengths of unidirectional CFRPs were estimated by considering the apparent shear modulus. The estimated results for various types of unidirectional CFRP showed good agreement with the experimental results. Upper and lower limit of the compressive strengths of the unidirectional CFRPs were found out theoretically.